N,K = map(int,input().split())
dat = [0] * (N + 1)
from collections import defaultdict
d = [defaultdict(int) for _ in range(N+1)]
n = N
for i in range(2,N+1):
    if dat[i] == 0:
        for j in range(i,N+1,i):
            dat[j] = 1
        u = i
        count = 0
        while n % i == 0:
            count += 1
            n //= i

        c = 1
        while u <= N:
            for j in range(u,N+1,u):
                d[j][i] += 1
                if c <= count:
                    d[j][-1] += 1
            c += 1
            u *= i
M = 0
div = 0
for i in range(2,N):
    if d[i][-1] >= K:
        tmp = 1
        for k in d[i]:
            if k == -1:continue
            tmp *= (d[i][k] + 1)
        if tmp > div:
            div = tmp
            M = i
print(M)